Relationship between CarPlay and External Accessory and Wireless Accessory Configuration

For my current project I am supposed to develop a IAP2 over USB connectivity to a Head Unit (MFI certified) that is developed by a 3rd party.

The requirement continuously uses the term 'CarPlay connectivity' for that feature. But without being able to dig deeper into CarPlay documentation (which is restricted for MFI enrolled developers only) I am left to speculate if CarPlay is actually the right term. As external Display + Car Input + Audio is explicitly NOT requested. I doubt that CarPlay is actually the correct term, but I can not be 100% sure.

I have already developed IAP2 over Bluetooth and all I want now is to use the same IAP2 protocol over USB.

So my questions are:

1. What is the difference between CarPlay and the pure use of the External Accessory framework?
2. Is there a difference between ExternalAccessory over Bluetooth and ExternalAccessory over USB concerning entitlements and declaration of IAP2 protocol identifiers?
3. How is the Wireless Accessory Configuration capability related to CarPlay?

1. Carplay over USB is usb host mode, the External Accessory protocol can be EA session or EA Native. BT is using EA session.
2. If consider EA Session, BT and USB are the same.
3. Accessory should able to transfer wifi related security configuration to iPhone.